# s1 = 'abc'
# for ch in s1:
#     print(ch)
# print('*' * 30)
#
# nums = [101, 123, 2000]
# for i in nums:
#     print(i)
# print('*' * 30)
#
# users = ('tom', 'jerry', 'bob')
# for user in users:
#     print(user)
# print('*' * 30)
#
# adict = {'name': 'tom', 'age': 20}
# for key in adict:
#     print(key, adict[key])

result = 0
for i in range(1, 10000001):
    result += i

print(result)
